An United States Postal Service manager allegedly stole $630,000 in stamps from a Louisiana post office, sold them online and used the proceeds to fund large casino expenses, according to federal charges announced Wednesday.

Ryan S. Cortez - the manager of customer service operations at the North Kenner Post Office in Kenner, Louisiana - has been charged with misappropriation of postal funds or property, United States Attorney Peter G. Strasser announced in a release.

Strasser's release said the alleged crime was "one of the largest internal Postal (thefts) by a Postal Service employee in the history of the U.S. Postal Service."

Authorities began investigating Cortez after PayPal and eBay notified Postal agents that Cortez had been selling "significant quantities" of stamps online, the release said. An investigation revealed that Cortez had increased his post office's stamp orders by more than $600,000.

Even though Cortez' salary was around $70,000, investigators found he had lost more than $650,000 at a casino since 2011, according to the United States Attorney's office. The release says Cortez lost more than $220,000 at the casino in 2017.

Cortez is also accused of embezzling thousands of dollars from a local Mennonite church. He faces up to 10 years in prison and a $250,000 fine if convicted, a release says.